1. Field of the Invention
The present invention relates to multi-layer woven fabrics, and more particularly to fabrics having thicknesses comprised of multiple yarn layers and other yarns extending through and interwoven with the yarn layers.
2. History of the Prior Art
It is known in the art of multi-layer woven materials to weave a fabric from a plurality of different yarn systems which provide the fabric with multiple interwoven layers or plies of thickness. Fabrics of this type can be woven using a circular loom such that the fabrics have an essential circular makeup or configuration. Fabrics of that type are illustrated by U.S. Pat. No. 3,749,138 of Rheaume et al, which patent issued July 31, 1973 and is commonly assigned with the present application. The Rheaume et al patent describes the weaving of a multi-layer fabric which is comprised of angled warp yarns extending through the thickness of the fabric and interwoven with fill yarns which extend along the length of the fabric in an orientation generally parallel to one another and to the opposite broad surfaces of the fabric and perpendicular to the warp yarns. A third or stuffer yarn system may be present such that generally parallel stuffer yarns extend across the width of the fabric in orientations perpendicular to the fill yarns.
Multi-layer fabrics may also be woven in a non-circular configuration such as in other curved configurations or in a generally rectangular configuration using conventional weaving apparatus. An example of such woven configurations is provided by U.S. Pat. No. 4,312,913 of Rheaume, which patent issued Jan. 26, 1982. The Rheaume patent illustrates fabric produced by an angle weave in which lengths of fill yarn disposed in a nominally parallel configuration are interwoven with angled warp yarns. The warp yarns extend in a zig-zag configuration through the thickness of the fabric between the opposite broad surfaces thereof so as to form a succession of intersecting warp sheets. The warp sheets intersect with and form acute angles with the opposite broad surfaces of the woven fabric. In the woven fabrics of the Rheaume patent, the warp yarns which extend in angled fashion through the entire thickness of the fabric are comprised of high heat conductivity compositions which may be different from one another as well as from the compositions of the fill yarns, and which are designed to maximize the flow of heat through the thickness of the fabric from an adjoining substrate. In addition to or in lieu thereof, the fill yarn layers may be interleaved with stuffer yarn layers of different composition.
The multi-layer woven fabrics described in U.S. Pat. No. 3,749,138 of Rheaume et al and U.S. Pat. No. 4,312,913 of Rheaume are typical of woven angled fabrics in which one yarn system, typically the warp yarn system, extends through the entire thickness of the fabric to provide an integral, tightly woven multi-layer fabric having generally uniform properties throughout the thickness thereof. Such structures are advantageous for many applications calling for multi-layer fabrics with good structural and other properties. However, it may be desirable for certain applications to provide multi-layer woven fabrics which not only have the advantageous structural characteristics of such fabrics but which also are customized in their construction so as to optimize different material properties or characteristics throughout different portions of the woven fabric. For example, it may be desirable to provide a woven fabric having high resistance to thermal or electrical conductivity through the thickness thereof in spite of a tightly woven configuration in which some of the yarns extend through the entire thickness of the fabric. Other applications may suggest the presence of high oxidation resistance material at a surface of the fabric but not throughout the remainder of the fabric. Still further applications may suggest a fabric having an ablative surface, chemically resistive properties or optically reflective properties.